Embankment Failures during the Historic October 2015 Flood in South Carolina: Case Study

The collection of time-sensitive data on real-life embankment failures and their analysis are essential steps to model breach processes and the consequential flood, which are of great importance for preparing emergency action plans. In this paper, data on 14 earthen embankments that failed or were damaged in the Midlands of South Carolina resulting from the historic 1,000-year storm during October 2015 are presented and analyzed. The investigation includes measurement of breach dimensions, collection of undisturbed soil samples, soil classification, embankment erodibility tests using the submerged jet erosion test (JET) method, calculation of peak discharge, estimation of maximum height of overtopping, and calculation of maximum reservoir volume behind each embankment at the time of failure. Using this information and results, single-variable and multivariable parametric breach models for the breach depth and breach width are developed and compared with selected breach models available in the literature. All the models except for one estimate the breach width satisfactorily, with the proposed single-variable equation giving a relatively better prediction. The collected data set of this study may be used by others for model verification.